It's
always kind of interesting to receive a prototype heatsink for testing,
especially when it comes with a full set of blueprints explaining how the whole
thing is put together. The Phoenix 70 (model No. 401100) is a new heatsink
from JMC Products that might remind more than a few of you of the old
Arcticooler from Agilent Technologies. That heatsink has been wiped from the corporate slate, but its memory lives on in the form of JMC
Phoenix 70 which even has a little Arcticooler logo on it.

The original Agilent heatsink
was made for socket 370 Pentium III processors, but this version is intended for
use with socket 478 Pentium 4's or Socket 603/604 Xeons. The unit we tested was
configured for socket 478.

What makes the JMC Phoenix 70 so
interesting is that the heatsink fins are cut from a single block of aluminum in
a radial 360 degree pattern. The 67mm diameter fan impeller is mounted inside a
ring of thin fins and when the heatsink is in operation two separate air
flow streams are created. The first stream consists of air as it is
sucked into the fan through fins at the top of the heatsink. The second
stream is created as exhaust air is pushed out through the fins at the
base of the heatsink.

Unlike a host of Taiwanese
heatsinks which use similar techniques now, or in the past, this is not
simply an extruded heatsink which has been machined to flat ninety degree angles
below the fan, fins extend all the way to the base of the fan motor.
The internal geometry of the Phoenix 70 has the fins at a slight angle
which helps provide a non-turbulent airflow that creates very
minimal noise. This is not to say the heatsink is silent, but is
does have its own very unique low frequency sound signature of about 53dB
in amplitude.

As JMC tend to be
a high volume manufacturer things are kept quite simple on this cooler - there is no copper or
heatpipe insert in the base, though such additions could produce very interesting results if they are ever added in the
future.

The basic construction consists of the main finned
heatsink inserted into an aluminum base which is suited for standard socket 478
spring clips. The edges of the base are slightly raised up as you can see, and
the corners of the cylindrical finned section notched out. The processor makes
direct contact with the central core (which is good), and the surrounding plate
is only used to keep the heatsink in position.

Because
the unit we tested was a prototype there were a few cosmetic differences you will
see in this review. The fan impeller had been cut down from a
larger size and so the edges of the blades were still a little fuzzy. This
didn't impact the sound signature of the fan by any significant degree
as the blade tips were cleaned up prior to
testing. The base of the heatsink was held
in place with an extra set of machine screws, but it is unlikely that this
will be the case with the final commercial version. And lastly, there was
some vibration issues due to the modified fan impeller which I expect would not
be carried over to consumer versions using standard fan assemblies which are
balanced.